句型转换。

1. We will hold a sports meeting tomorrow. (改为被动语态)

    A sports meeting_______ ________ ________tomorrow.

2. You can keep the book for a week. (对画线部分提问)

     ________ ________ ________ ________ keep the book?

3. I became a teacher in 2001. (同义句转换)

    I _______ ________a teacher ________ 2001.

4. He went to England two years ago. (同义句转换)

    He________ _________ ________England________two years.

物理学上把某种物质单位体积的______叫做密度．冰的密度为0.9×10³千克/米³，读作0.9×10³______，表示的意思是每立方米冰的______．2千克冰全部熔化成水后，水的质量为______千克，体积变为______米³．